Recently, a pronounced preference tendency on a high-resolution/high-definition image is demonstrated due to the development of hardware and the use of various multimedia devices, requirements of which have led to the industrialization of various high-resolution devices. Moreover, due to the development of various terminal devices, it is necessary to support scalability enabling to adaptively use in the various terminal devices in the field of a video codec.
Generally, among various video codecs supporting scalability, a Scalable Video Codec (SVC) demonstrates the most excellent performance. Up to now, since the SVC supports only YUV 4:2:0 format and conversions on chrominance spaces other than it should be performed in the outside of the video codecs, the video codecs have limitations. Moreover, methods have been proposed that enable the SVC to support a high resolution in various schemes, but the SVC merely supports only one chrominance space.
For example, in a case where a lower layer uses the chrominance space of the YUV 4:2:0 format and an upper layer uses a chrominance space, which is different from that of the lower layer, such as RGB 4:4:4 format, a chrominance conversion using a chrominance converting formula and a floating operation should be performed, and which chrominance conversion formula is used must be known for inter-layer prediction coding. However, it is impossible to use a scalability technology capable of performing the chrominance space conversion with only information defined in a related art SVC.
Accordingly, since a server must store video streams for each of various digital devices using video streams of layers having different chrominance spaces, it wastes too much storage space.